The European Central Bank kept rates at 1.25 percent on Thursday, and President Jean-Claude Trichet suggested at a news conference that a rate rise wasn't likely next month but could happen in July, Reuters reported. (Watch a stream of the press conference live on CNBC.com)

"We will continue to monitor very closely all developments," with respect to price stability, Trichet said.

According to analysts, the use of the phrase "monitor very closely" upside risks to price stability, would signal a rate rise in July, while the phrase "strong vigilance" would signal a rise in June.

The dollar gained against a basket of currencies on the news, while the euro sank.

And oil pricessharply fell amid concern about a reduction in demand and rising interest rates. London Brent crudefell more than 3 percent to nearly $117, while U.S. light crude fell nearly 3 percent to nearly $106.

In earnings news, General Motors traded flat to slightly lower despite beating both profit and revenue expectations. The once bankrupt automaker credited sales in North America and Asia for the gains.